The Laboratory Sheep colony, Contract Number N01-HI-7-2900 in its fifth year, has continued to meet specific animal model requirements of IR laboratories including principally CHB, LTD and SB, as well as NICHHD, IRP laboratories including PRB and LBS. Practices that have contributed to the reduction of undesired production variables include: (1) continuous prophylactic immunization of various age groups; (2) accurate pregnancy diagnosis using Doppler ultrasound; (3) monitoring of animal health using various diagnostic laboratory techniques and (4) many other husbandry techniques unique to this colony. Such practices are cost prohibitive in commercial sheep flocks which results in an unreliable supply of disease-free animals that meet the requirements of biomedical research.